Fabric



April 1941' H. BRADSHAW 2,238,098

FABRIC Filed July 28, 1938 Pa Waiya Y/zrezzdr P ml; (A1 \.L-' 1! Ag AGround M1170 Threads Ground Weft Threads" Hamdfimn rsha/u) INVENTOR.

ATTORNEY Patented Apr. l5, 1941 UNITED STATES PATENT OFFICE .FABBICHamilton Bradshaw, Wilmington, DeL, asslgnor to E. I. du Pont de Nemours8; Company,

Wil-

mington, Del., a corporation of Delaware Application July 2a, 1938,Serial No. 221,732

2 Claims. (Cl. 139-391) in damp weather is anotherdisadvantage fre- Thisinvention relates to the production of pile fabrics, such as velvets,transparent velvets, plushes, mohairs, carpets, fur-like fabrics and thelike, from synthetic linear condensation polyamides.

Pile fabrics comprise a large part of total textile production sincethey are pecularily suitable for a large variety of purposes. There aremany types of pile fabrics adapted to different uses. These are producedby various constructions and combinations of pile elements-and groundfabrics, respectively. These constructions and combinations of the sameor different textile filaments will be described more fully hereinafter,but regardless of the type of pile fabric, there are certain commonproperties desired of all.

One of the most important of these is that the pile be permanently crushresistant. Although the term "crush resistant" is widely used in theart, it should not be interpreted literally. The most desirable pile isnot one which resists deformation but rather one which is easilydeformed and returns readily to its original position when the load isremoved. In other words, what is really desired is recovery fromcrushing or true elasticity. Any attempts to prevent permanentdeformation by using coarser piles or by stiffening them are thereforenot desirable since they detract from the attractiveness of the hand aswell as the utility of the fabric.

Although wool, silk, mohair and other natural products are fairlysatisfactory as pile elements within certain limits of load, temperatureand humidity, their utility is limited. Synthetic filaments such asregenerated cellulose rayon have been used as the pile in pile fabrics,for example. in transparent velvets, but its crush resistance is so poorit has been very desirable if not necessary to subject it to certainchemical treatments to improve its properties. These chemical treatmentsmay result in a stiffening of the pile and unless carefully controlled,embrittle it, and for this reason they are disadvantageous. The propertyof crush resistance should be permanent and should remain constant underall conditions of humidity and temperature.

It has always been necessary to produce certain types of pile fabricssuch as plushes, mo-

hairs, etc., using wool. The effect of the attack F of moths on thesefabrics constitutes a grave problem and much expense is incurred inspecial mothproofing treatments. This same diiliculty is alsoexperienced with natural furs. The development of musty odors from somepile fabrics quently experienced.

Heretofore certain, problems were encountered in the actual productionof pile fabrics. Among these was the difficulty in obtaining a pile ofuniform length. Piles of uniform length were obtained only by repeatedshearings accompanied by steaming and brushing operations, the steamrendering the pile more plastic and permitting its rearrangement bybrushing. These operations are expensive and represent a large share ofthe total cost of the finished fabrics. Likewise, these repeatedsteamings tend to reduce the resiliency of the pile.

Another difficulty previously experienced was non-uniform dyeing. Thistakes two forms: that of ordinary dyeing differences common to manytextiles, especially those made from natural materials; and another moreserious problem sometimes referred to as greighing off. This wasexperienced in pile fabrics with a pile of high denier and ischaracterized by difference in penetration of the dye into the pileelements, with accompanying differences in depth of color across thecross-sectional area. This difficulty is often experienced with mohair.

While the pile elements of pile fabrics have been discussed, the choiceof the ground fabric is also very important. Natural silk has been usedalmost exclusively as the ground warp for the production of pile fabricsfor dress goods such as transparent velvet. The use of silk for thispurpose has presented many dimculties. To obtain the desired sheerness,strength, hand, elasticity, etc., it is necessary to use the bestquality silk. Since silk is a natural product, it is dependent upon thevariations of supply, world conditions, etc., and the problem is furthercomplicated by this necessity of using only the best grade of silk forthis purpose. The use of silk as the ground fabric presents a seriousdimculty peculiar to silk itself. Silk has a closely adhering coating ofa gum called sericin. This gum aids materially in the manufacturingoperation, preventing damage during weaving. After a pile fabric hasbeen prepared using silk as the ground warp, it is necessary to removethis sericin. This is commonly called a boll-off treatment, and is quitesevere. This finishing process interferes with the appearance andquality of the pile. This is especially serious with a cellulosederivative rayon pile, since the treatment necessary to remove thesericin saponifies the cellulose derivative pile and seriously damagesit, so that it is of little use. This finishing treatment is also veryexpensive and represents an appreciable part of the total cost of thefabric.

It has long been desired to provide the art with a high grade of pilefabrics, especially dress fabrics such as transparent velvet, madeentirely of synthetic filaments. Although regenerated cellulose rayonhas been used as the pile element, it has been very desirable, if notnecessary, to treat the pile to improve crush resistance, as indicatedabove. Since this treatment must be selective to the pile asdistinguished from the ground fabric, the choice of ground fabrics has,therefore, been decidedly limited.

It is, therefore, an object of this invention to produce new and usefulpile fabrics.

It is another object to prepare a pile fabric having a high degree ofpermanent crush resistance without stiffening of the pile.

Another object of this invention is to prepare a high grade of pilefabric which is constructed entirely from synthetic filaments.

The objects of this invention are accomplished, in general, by usingsynthetic linear condensation polyamide filaments for the constructionof pile fabrics. The synthetic linear condensation polyamide filamentsserve exceedingly well for use in the pile threads, the ground warpthreads or the filling threads of pile fabrics. As a consequence theentire pile fabric may be constructed of these synthetic filaments withexcellent results.

The accompanying drawing illustrates, in a single figure, a pile fabricconstructed in accordance with the present invention.

Referring to the drawing the pile fabric i11ustrated is comprised ofground warp threads, ground weft threads and pile warp threads, as shownby legends in the drawing. Preferably, the various threads of the pilefabric are all composed of synthetic linear condensation polyamidefilaments.

Fiber-forming synthetic linear condensation polyamides and fibersproduced therefrom are described in U. S. Patents Nos. 2,071,250,2,071,- 251, and 2,071,253. The term synthetic linear condensationpolyamides includes two types of polymers-those obtainable frommonoaminomonocarboxylic acids and those obtainable from the reaction ofsuitable diamines and dibasic carboxylic acids. The diamine-dibasic acidpolymers are described in greater detail in the U. S. patent applicationof W. H. Carothers, Serial No. 136,031, filed April 9, 1937. Thefilaments which are preferable to use are made from polyhexamethyleneadipamide, the polymer derived from hexamethylenediamine and adipicacid. While in some modifications of this invention, unorientedsynthetic polyamide filaments may be used, it is preferable in mostcases to use the oriented synthetic polyamide fibers.

The methods of preparing pile fabrics are well developed. One of thebest known makes use of a double shuttle loom which uses two sets ofground warp and filling yarns to weave two backings or ground fabricswhich are held together by a pile warp which is common to both backingfabrics. Through the use of a cutting apparatus, the fabric is cut onthe loom in two separate pieces. Many velvets and plushes are producedin this manner.

In another process, an extra set of warp threads are formed into loopsby passing them over wires whose upper edges are sharp, or which have acutting attachment on one end. The loops are fastened in while the clothis being woven and are cut as the wires are removed. Uncut velvets andplushes may be produced in a similar manner, using wires which do notout the loops.

In certain types of pile fabrics, the pile comes from an extra fillerthread mechanically projected from the body of the cloth at regularintervals to form loops or fioats. After weaving, these are cut andbrushed up to form the pile. Materials such as corduroy, velveteen,etc., are made in this manner. An uncut pile (known as terry weave) isfound in turkish toweling and in some upholstery fabric. Another exampleof an uncut pile is a frieze.

Further types of pile fabrics and artificial furs are prepared byknitting or weaving pile elements consisting of short, loose fibers inwith a base strand such'as a chenille. Fibers may also be sewed on aprepared backing, or attached by means of adhesives.

J. B. Miles, Jr., in his copending application, Serial No. 125,941,filed February 15, 1937, discloses that these linear polyamidefiberstend to become set in the condition or shape in which they areexposed to steam. Hot water, hot alcohols, e. g., methanol and ethanol,hot aniline, or other non-solvent swelling agents also have a similareffect. To achieve a more crushproof and satisfactory pile, it has beenfound that the polyamide fibers should be set when in the condition orposition ultimately desired. To that end, fibers will preferably beemployed which have not previously been set, since they can be resetonly by a more rigorous treatment.

While similar treatments have previously been applied to pile fabricsmade from other materials followed by brushing and other operations, theeffect of the steam has been temporary and any setting action has beenaccomplished only by the process of drying out. As already indicated,however, the most satisfactory fabrics are obtained by setting apolyamide pile in a position ultimately desired by treatment with steamor other agents having a setting action on the polyamide. This treatmentsets the pile in a more or less permanent shape, to which it recoversafter deformation. The setting treatment, therefore, improves the crushresistance of the pile and is of a permanent nature. Likewise, such atreatment applied to pile fabrics comprising synthetic polyamide fibersas the ground fabric renders them, by virtue of the same setting action,substantially creaseproof. Similarly, when this steam treatment isapplied to pile fabrics comprising both the pile element and groundfabric of synthetic polyamide fibers, the fabric is rendered creaseproofand crushproof during the same treatment.

The following examples are illustrative, but are not to be considered aslimitative of the invention:

Example I A transparent velvet was constructed using 35 denier filament10 turn 8". twist dull yarn of oriented polyhexamethylene adipamide inthe ground warp and denier 10 filament turn S twist yarn of orientedpolyhexamethylene adipamide in the ground filling. The pile warp wasmade from 100 denier filament 4 turn bright yarn of orientedpolyhexamethylene adipamide. The yarns used in the ground warp andfilling were treated prior to coning for one hour with air 76.6 C. drybulb, 71.2 C. wet bulb, which condition reduced the llveliness of thetwist sufficiently to permit subsequent handling. The

pile warp yarn was not subjected to this treatment. The fabric was wovenin the usual manner on the double shuttle looms, cut and subjected tothe usual dyeing, trimming and brushing operations. As the finaltreatment when the pile had been brushed to a straight condition, thefabric was held on a tentering frame, exposed to the action of saturatedsteam at atmospheric pressure for minutes, and subsequently dried withhot air. Under these conditions, it was found that the resulting fabrichad a very satisfactory appearance and texture and that it waspermanently resistant to crushing.

Example II An upholstery fabric comparable to a natural mohair wasconstructed using warp yarn of 24/2 cotton, with 15 turns per inch inthe ply. The filling yarn was 32/2 cotton, with turns per inch in theply. The pile yarn was 740 denier 80 filament 7 turn orientedpolyhexamethylene adipamide. This fabric was woven in the usual manneron a double shuttle loom, but an attachment was added to the loom infront of the cutting mechanism, so that the freshly woven fabric couldbe subjected to the action of saturated steam at atmospheric pressurefor 10 minutes. After steam treatment, the fabric was subjected to thenormal cutting operation, splitting the double fabric into its twocomponent fabrics. The appearance of the pile of these fabrics was verysatisfactory and the cutting was so even that it was not necessary tore-shear in order to obtain a uniform pile. Likewise, it was found thatthe pile had dyed very uniformly. The resulting fabric was remarkablefor its resistance to crushing, even at high relative humidities, whichare frequently encountered in using the fabric as automobile upholstery.The crush resistance of the polyamide pile fabric at 50% R. H. wascomparable to that of a mohair upholstery fabric and at 98% R. H. it wasgreatly superior to the mohair fabric.

Example III A transparent velvet was constructed using denier 10filament 10 turn S twist dull oriented polyhexamethylene adipamide yarnin the ground warp and 35 denier 10 filament turn 8" twist orientedpolyhexamethylene adipamide yarn in the ground filling. The pile warpwas 100 denier filament 4 turn regenerated cellulose yarn produced bythe viscose process. The yarn used in the ground warp and filling wastreated prior to coning in a manner similar to that described in ExampleI to remove the liveliness of the twist. The fabric was woven; cut, andsubjected to the usual dyeing, trimming and brushing operations,

after which it was subjected to a formaldehyde treatment, as disclosedin Heckert U. S. No.

2,080,043 to render the pile crushproof. The re'-- sultant fabric wasvery strong, superior in strength to a silk backed-fabric and the pilewas more attractive since it was not necessary to boil off to removesericin.

Example IV The pile because the cellulose acetate pile had not beensubjected to a boil-off treatment.

Example V An filament 200 denier yarn prepared from orientedpolyhexamethylene adipamide fibers was wound on a fiat metal guide(Singercraft attachment), having a slit at one side of the center and acutting attachment at the end. The yarn was sewed to a cotton backing,the seam being through the slit in the guide. Upon completion of thesewing, the metal guide was withdrawn, cutting the row having the largerloop. Consecutive parallel rows of loops, spaced from V; inch to inchapart, were sewed on cotton in the same manner, so that the closelyoverlapping rows of pile gave a thatched, fur-like effect. The resultingpile fabric was then stretched on a tentering frame, the rows of pilecarefully arranged in the ultimately desired position. A screen was thenplaced on the pile surface to maintain the pile in this position, thefabric treated with boiling water for ten minutes. The screen was thenremoved, and the fabric dried in air at 76.6" C. The resulting fabrichad a very attractive pile, arranged in the desired configuration, andwas permanently very resistant to disarrangement.

In the production of pile fabrics with yarns composed of syntheticlinear condensation polyamides a wide range of filament and thread sizescan be employed to serve the various objects above set forth. The pilewarp threads may have a denier of from 50 to 2000 depending upon whetherthey are to be used for sheer transparent velvet or for upholsteryfabrics or rugs. The filaments of such pile threads may vary from 0.2denier to 6 denier per filament in transparent velvet to 10 to 20 denierper filament in rug constructions. Ground warp and filling yarns willvary from 25 denier 170,300 denier and these threads will be composed offilaments having a denier of 0.5 to 10, depending upon the particularfabric construction.

The number of synthetic linear condensation polyamide yarns per inchused in the various fabric constructions will also vary greatly. Intransparent velvet the pile warp yarns may be spaced closely together soas to have from 25-to '75 yarns per inch; on the other hand, in theproduction of imitation furs the pile yarns may be spaced from eachother so as to have only 4 to 20 yarns per inch. Ground warp and fillingthreads will vary from 20 to threads or pics per inch depending upon thetype of fabric construction.

In the preparation of fur-like materials, it is sometimes desirable touse fibers of more than one size and length, the long fibers being of alarge denier and the shorter ones being very fine and soft to the touch.Furthermore, it is sometimes desirable to use tapered filaments, thusmore closely simulating natural furs. Likewise, it is desirable in manyfur-like materials to have the pile recline in one direction, as in anatural pelt. This is especially important when the fabric is to be usedin outer garments to shed water. This condition can be accomplished byarranging the pile in a desired way and setting it.

Crimped or curly forms of the fiber may be used in essentially the samemanneras a straight fiber. This is of special advantage in giving asoft, resilient, fur-like pile. A novel fabric can be made by completingthe crimping process on the pile filaments after incorporation in thefabric, This can be done by using as the pile warp spontaneouslycrimpable polyamide filaments prepared by the process of copendingapplication of Hardy and Miles, Serial No. 183,922, filed January 7,1938.

- spontaneously crimpable filaments in the pile warp, the crimpablefilaments are held under tension by the fabric structure until the pileis cut. Before cutting the pile, therefore, it is necessary to wet thepile unless it is already wet. After cutting, the fabric is dried,whereupon the pile crimps spontaneously. The crimp may be rendered morepermanent by steam treatment which also improves the crush resistance ofthe pile. The curly pile has unusually good covering power.

Unoriented synthetic polyamide filaments may also be used as the pileelements. If desired, these pile elements may be subjected to colddrawing after being woven into a pile fabric. Novelty effects may beobtained by drawing only a part of the pile elements thus producingpiles comprising intermingled short and long filaments of different orthe same cross-section. Such a process is valuable in the production ofartificial furs.

The use of delustered fibers, colored fibers, and fibers containingplasticizers or waterproofing agents is within the scope of myinvention. Likewise, for certain purposes, finish, size or othermaterials may be applied to the fibers at some time prior to, during, orafter weaving. Waterproofing compositions or compositions which willcause the fabrics to shed water may be applied. Such treatments areespecially valuable for those fabrics exposed to the elements as innatural furs.

I have not specified whether I prefer to use shrunk or unshrunkfilaments for the pile. I have found that I can use both successfully.For certain purposes, shrunk yarn may be desirable, in which case Iprefer to subject the yarn to a shrinkage treatment which will not setit relative to the setting in the final form in the fabric. This canconveniently be accomplished by exposure to dry heat in a relaxedcondition for a short period at a temperature of 140 C.

While it would be expected that synthetic polyamide filaments which havebeen shrunk would be preferred for use in the ground fabric since theshrinkage of the fabric during subsequent treatments would be prevented,this is not always the case. These synthetic polyamide filamentsnormally have a high residual shrinkage (approximately 10%) and thisproperty can be used to advantage especially in the preparation oftransparent velvet. The residual shrinkage is determined by subjecting ameasured sample to an aqueous treatment with or without detergents at atemperature of 95-100 C. for several minutes. This sample which has beensubjected to this shrinking treatment in the relaxed condition is thendried in a relaxed condition and its length determined at the samehumidity and temperature as the initial measurements. The shrinkage ofthe yarn after the production of the fabric eliminates the necessity ofusing a yarn of high twist required when natural silk is used as theground warp and filling. This shrinkage of the ground fabric results ina pile fabric with a denser and more erect pile. The ground fabric isstronger and permits the use of filaments of finer denier since thisshrinkage brings the warp and filling elements even closer together thanthey can normally be woven. The pile fabrics so produced have asatisfactory hand, are quite compact, and have a very attractiveappearance.

By the setting treatment I am able to produce fabrics with many noveleffects. In many rugs and carpets it is desirable to have the pilerecline uniformly in a certain direction. This is commonly done bymechanical means, such as particular methods of weaving or tying thepile. Some of these methods, as in the production of oriental rugs, arenot adaptable to machine operation. Other methods which are adaptable tomechanical operation are still expensive due to the type ofconstruction, etc. These fabrics can be easily and cheaply simulated byarranging the pile in the desired conformation and setting it while heldin that position.

Similarly, other novelty effects can be produced by intentionaldisarrangement of the pile in various ways. This disarrangement may beextended throughout .the fabric, or it may be confined to predeterminedareas. The nature of this disarrangement may be uniform, or of variouscombinations becoming readily apparent. In each case, the desiredarrangement may be restrained against further change by setting.

Pile fabrics comprising these synthetic polyamides when out into smallsegments have high bulking value and are useful as down substitutes instufilngs for pillows, upholstery and comfortables especially in view oftheir resistance to attack by mold and insects, low heat conductivityand low moisture absorption. Either straight and/or crimped filamentsmay be used for this purpose. Cut chenille is particularly advantageousas a down substitute.

The use of synthetic polyamide filaments in pile fabrics has certainimportant advantages over other filaments, natural or synthetic, bothfrom the standpoint of fabrication and utility of the product. When usedas the pile, one of the most important advantages is that the pile hasan attractive hand and is inherently and permanently crush resistant.The pile is crush resistant without being stiff; in other words, it istruly resilient. This resiliency is especially valuable in upholsteryfabrics since their surface has less frictional resistance than similarfabrics constructcd from other materials. This permits ready movementwhen seated upon such fabrics which is very important in automotivevehicle upholsteries. This property of true resiliency and the decreasein stiffness is also valuable in that the prickling sensation commonlyassociated with pile fabrics is not present. Likewise, this resistanceto crushing is maintained under conditions of high humidity andtemperature. The moisture content of the filaments comprising thesefabrics in equilibrium with atmospheres of high humidity is less thanthat of filaments previously known. Similarly, the fabrics arepermanently mothproof and moldproof and do not develop musty DMOI'S indamp weather.

The pile is attractive because of its hand and because of its uniformityof dyeing, absence of greighing oil. and the uniformity of the pile. Thepile retains its 'good appearance because of its crush resistance andhigh abrasion resistance. In fabrics having a cut pile, due to theresiliency of the synthetic polyamide filaments, the pile can be outvery uniformly. Costly and damaging brushing, steaming and re-shearingoperations are eliminated. The pile has good insulating properties andis not easily damaged.

When the synthetic polyamide filaments are used in the ground fabrics,the pile fabrics produced are strong and elastic, permitting theproduction of sheer fabrics and fabrics which are creaseproof. When usedin combination with synthetic polyamide pile, the crush and creaseresistance can be improved by the same hot wet treatment. Since noboil-01f. is required, for ground fabrics comprising these syntheticpolyamides, they may be used with other filaments as the pile elements.It is, therefore, possible to use successfully other synthetic filamentssuch as cellulose derivative or regenerated cellulose rayons. Pilefabrics produced completely from syn thetic filaments of various typesof filaments as well as from the same type of filament are, therefore,possible.

Since it is obvious that many changes and modifications can be made inthe above-described process without departing from the nature and spiritof the invention, it is to be understood that the invention is not to belimited except as set forth in the appended claims.

Iclaim:

i. As a new article of manufacture an improved dense pile fabriccomprising ground warp and weft threads and pile threads, the groundthreads of which are composed essentially of synthetic linear polyamidefilaments, the ground threads being shrunk, in situ, in the fabricwhereby to increase the denseness of the pile.

2. As a new article of manufacture an improved dense pile fabriccomprising ground warp and weft threads and pile threads, the groundthreads of which are composed essentially of polyhexamethylene adipamidefilaments, the ground threads being shrunk, in situ, in the fabricwhereby to increase the denseness of the pile.

HAMILTON BRADSHAW.'

